Multiple-disc type filters are known generally and include a housing in which is disposed a filter body in the form of a stack of like, centrally-apertured, filter discs of substantially uniform thickness along their widths. The individual discs have grooved side faces defining filtering channels between the adjacent discs in the stack.
Multiple-disc type filters have a number of advantages over other known types of filters, for example the cylindrical screen type filter, in that the multiple-disc filter has a relatively large capacity for removing and retaining dirt particles, since these may be retained between the side faces of the discs in addition to being retained on the upstream surface of the filter. The multiple disc filter is also characterized as being relatively easy to clean and resistant to rupture and is operative even at relatively low pressures.
In my copending U.S. patent application Ser. No. 709,372, filed on Mar. 7, 1985 now U.S. Pat. No. 4,683,060 dated July 28, 1987 and claiming priority from Israel Patent Application No. 73923 there is described a disc-type filter including a housing having an inlet connectable to an upstream pipe, and an outlet connectable to a downstream pipe; and a stack of discs disposed within the housing for separating solid particles from a fluid flowing between the discs from the upstream side of the stack to the downstream side thereof; characterized in that the stack includes:
a plurality of cooperating filter elements defining a plurality of paired co-operating filter surfaces, including a first surface having a large surface area and a second surface contacting only a portion of the large surface area of the first surface and leaving a portion of the large surface area on the upstream side of the stack not contacted thereby, at least one of said first and second surface being formed with grooves at the areas at which the first and second surfaces contact, thereby to form: PA0 a plurality of cooperating filter elements defining a plurality of paired co-operating filter surfaces, including a first surface having a large surface area and a second surface contacting only a portion of the large surface area of the first surface and leaving a portion of the large surface area on the upstream side of the stack not contacted thereby, at least one of said first and second surfaces being formed with grooves at the areas at which the first and second surfaces contact, thereby to form:
a) compartments on the upstream side of the stack for accumulation of solid particles; and PA1 b) edge filtering passageways extending along the grooves in contact with the second surface, which passageways define the minimum size of particles separated by the filter and extend from the compartments to the downstream side of the stack. PA1 a) compartments on the upstream side of the stack for accumulation of solid particles; and PA1 b) edge filtering passageways extending along the grooves in contact with the second surface, which passageways define the minimum size of particles separated by the filter and extend from the compartments to the downstream side of the stack, and wherein the second surface is formed with serrated edge surfaces defining the compartments on the upstream edge of the stack, thereby increasing the length along which edge filtering passageways are defined.